Cover the buttered bottom of a deep stewing pan with grated horseradish, put the portions of the fish fillet on it in two or three layers, in turns with grated horseradish. Add fish bouillon with vinegar and salt to the fish, cover and stew for 30 minutes.

Pour some clear soup in a separate bowl, add sour cream and bring to a boil. Stir in dry fried flour, warm on a low heat without boiling. Pour this sauce to the fish and stew for 10-15 minutes.

Serve the dish with boiled potato, cover with the fish sauce. Decorate with lemon slices, capers, parsley and dill greens